{"title":"Optolong SHO Filter Sets","description":"\u003cp\u003eMatched H-alpha, OIII and SII narrowband filter sets.\u003c\/p\u003e","products":[{"product_id":"optolong-sho-filters-set-3nm","title":"Optolong SHO Filters set 3nm","description":"\u003ch2\u003eNew 3nm Ultra Narrowband Astronomy Filters from Optolong\u003c\/h2\u003e\n\u003cp\u003eThis premium narrowband filter set includes \u003cstrong\u003eSII (3nm)\u003c\/strong\u003e, \u003cstrong\u003eH-Alpha (3nm)\u003c\/strong\u003e, and \u003cstrong\u003eOIII (3nm)\u003c\/strong\u003e filters, designed for high-resolution astrophotography of emission nebulae using monochrome CCD and CMOS cameras.\u003c\/p\u003e\n\u003cp\u003eUltra-narrowband imaging allows productive astrophotography even under strong moonlight or severe light-polluted skies, making it possible to maximise imaging opportunities on every clear night.\u003c\/p\u003e\n\u003cp\u003eData captured through each filter can be combined into a full-colour final image. A common approach is the \u003cstrong\u003eHOO palette\u003c\/strong\u003e, using H-alpha for the red channel and OIII for both green and blue channels. H-alpha data can also be blended into RGB images to significantly enhance contrast and fine structural detail while preserving a natural colour balance.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eH-Alpha 3nm Filter:\u003c\/b\u003e The most widely used narrowband filter for deep-sky imaging, passing a precise 3nm bandwidth centred at \u003cstrong\u003e656nm\u003c\/strong\u003e. This filter strongly suppresses artificial light sources such as mercury vapour and sodium street lighting, as well as natural skyglow caused by atmospheric oxygen emission. The result is exceptionally high contrast and the ability to reveal delicate nebular structures that are otherwise lost in broadband imaging.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eOIII 3nm Filter:\u003c\/b\u003e Designed for imaging emission nebulae at the \u003cstrong\u003e500nm\u003c\/strong\u003e oxygen-III emission line, allowing a 3nm bandwidth to pass. This filter effectively blocks artificial light pollution and unwanted atmospheric glow. OIII emission occurs at 495.9nm and 500.7nm, producing a characteristic blue-green colour. Many planetary nebulae and supernova remnants are imaged using only H-alpha and OIII filters, producing images with strong structure and naturally balanced colour similar to RGB data.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eSII 3nm Filter:\u003c\/b\u003e Optimised for imaging nebulae at the sulphur-II emission line centred at \u003cstrong\u003e672nm\u003c\/strong\u003e. With a narrow 3nm bandwidth, this filter efficiently blocks artificial light pollution and atmospheric skyglow, making it ideal for SHO (Hubble Palette) imaging where sulphur data adds depth and contrast to complex nebular regions.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eIMPORTANT:\u003c\/b\u003e \u003cstrong\u003eOptolong filters are NOT designed for solar observation or solar photography.\u003c\/strong\u003e DO NOT use these filters to observe or photograph the Sun. Doing so will result in \u003cstrong\u003epermanent eye damage\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cdiv class=\"product_features\"\u003e\n\u003ch2\u003eFEATURES\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003e85%+ transmission within the passband with precision off-band blocking\u003c\/li\u003e\n\u003cli\u003eInfrared wavelengths from 700–1000nm effectively blocked\u003c\/li\u003e\n\u003cli\u003eOff-band transmission limited to 0.1%, suppressing major artificial light pollution lines (Na 589nm, Hg 435nm \u0026amp; 578nm)\u003c\/li\u003e\n\u003cli\u003eSuitable for use with monochrome CCD and CMOS cameras\u003c\/li\u003e\n\u003cli\u003eAvailable in 2\" mounted or 36mm unmounted formats\u003c\/li\u003e\n\u003cli\u003eSupplied in a protective plastic case with EVA foam lining\u003c\/li\u003e\n\u003cli\u003eOptical glass thickness: 2mm (36mm), 1.85mm (2\")\u003c\/li\u003e\n\u003cli\u003eDouble-sided fine optical polishing ensures λ\/4 wavefront accuracy and \u0026lt;30 arc-second parallelism\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003ch2\u003eTransmission Chart\u003c\/h2\u003e\n\u003cp\u003e\u003cimg alt=\"Optolong SHO 3nm narrowband filter transmission chart\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/optolong_sho_3nm_transmission_chart.png?v=1769975587\"\u003e\u003c\/p\u003e\n\u003cp\u003eSII Line: H-Alpha, 3nm centred at 656nm.\u003c\/p\u003e\n\u003cp\u003eGreen Line: SII, 3nm centred at 672nm.\u003c\/p\u003e\n\u003cp\u003eBlue Line: OIII, 3nm centred at 500nm.\u003c\/p\u003e\n\u003ch2\u003eTechnical Data\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eSchott optical glass substrate\u003c\/li\u003e\n\u003cli\u003eThickness: 2.0mm (36mm), 1.85mm (2\")\u003c\/li\u003e\n\u003cli\u003eSurface Quality: 60\/40 (MIL-O-13830 standard)\u003c\/li\u003e\n\u003cli\u003eFine-optically polished to λ\/4 wavefront accuracy\u003c\/li\u003e\n\u003cli\u003e\u0026lt;30 arc-second parallelism\u003c\/li\u003e\n\u003cli\u003e85%+ transmission at passband\u003c\/li\u003e\n\u003cli\u003eInfrared cut-off from 700–1000nm\u003c\/li\u003e\n\u003cli\u003eHigh-precision off-band blocking\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eCoating Parameter\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eMulti-layer anti-reflection coatings\u003c\/li\u003e\n\u003cli\u003eNon-cemented optical substrate coating\u003c\/li\u003e\n\u003cli\u003eElectron-beam evaporation with ion-assisted deposition for enhanced durability and scratch resistance\u003c\/li\u003e\n\u003cli\u003eExcellent central wavelength stability with minimal temperature-induced shift\u003c\/li\u003e\n\u003cli\u003ePlanetary rotation coating system ensures uniform coating density and high optical performance\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eFilter Cell\u003c\/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUltra-thin filter cell minimises vignetting while maximising clear aperture\u003c\/li\u003e\n\u003cli\u003eClear aperture: 26mm (1.25\"), 45mm (2\")\u003c\/li\u003e\n\u003cli\u003eAerometal construction with precision CNC machining\u003c\/li\u003e\n\u003cli\u003eSand-blasted, black-anodised finish with internal anti-reflection treatment\u003c\/li\u003e\n\u003cli\u003eLaser-engraved markings for permanent identification\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2\u003eSample Images\u003c\/h2\u003e\n\u003cp\u003e\u003cimg alt=\"NGC7000 narrowband astrophotography image\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/optolong_sho_3nm_sample_1.jpg?v=1769975589\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eNGC7000 © Tommaso Massimo Stella\u003c\/b\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg alt=\"NGC6960 Veil Nebula narrowband image\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/optolong_sho_3nm_sample_2.jpg?v=1769975589\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eNGC6960 © Andrea Andreotto Maggi Astrophoto\u003c\/b\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cimg alt=\"Optolong H-alpha 3nm filter test image\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/optolong_sho_3nm_sample_3.png?v=1769975589\"\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eH-Alpha 3nm Test © YaGe\u003c\/b\u003e\u003c\/p\u003e","brand":"Optolong","offers":[{"title":"2\"","offer_id":42296205213873,"sku":null,"price":599.0,"currency_code":"GBP","in_stock":true},{"title":"36mm","offer_id":42296218058929,"sku":null,"price":643.0,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0523\/1650\/4241\/files\/Optolong-H-alpha-OIII-SII-3nm-narrowband-filter-HSO-set-2-inch-1000x1000w.webp?v=1769974573"}],"url":"https:\/\/www.darkclearskies.co.uk\/collections\/optolong-hub-sho-sets.oembed","provider":"Dark Clear Skies ","version":"1.0","type":"link"}